Desulphurizing gasoline



March 3, 1936. J. M. MCGEE ET AL DESULPHURIZING GASOLINE Filed Jan. 9, 1930 m M D wwm mw Rbberi M R08- 70 fllaorbed by Acid Patented Mal-.3,- 1936 Q I 2,032,662

UNITED STATES PATENT OFFICE DESULPHURIZING Glisoumi John M. McGee and Robert M. Roe, Casper, Wye, assignors to Standard Oil Company (Indiana), Chicago, 111., a corporationof Indiana N Application January 9,1930, Serial No. 419,544

10 Claims. (01.196-31) This invention relates to a process of desulble trays and battle plates. This tower, per se, phurizing gasoline and it pertains more particuforms no part of the present invention and will larly to an improved method of desulphurizing not be described in detail. cracked gasoline of high sulphur content. Stripping steam is introduced by pipe I4 to 5 The object of our invention isto provide a remove all low boiling point. hydrocarbons from 5 process for removing sulphur from high sulphur the naphtha bottoms, which are withdrawn cracked gasoline which will increase the yield of through pipe l5. Ahigh boiling fraction is withtreated gasoline and minimize the absorption of drawn from the tower at a point above the disgasoline in the treating acid (minimize the charge of pipe l2 by a pipe l6 which conveys this 19 amount of sludge formed). fraction to receiver ll.

A further object is to reduce the amount of The reflux vapors are conducted from the top acid required for removing sulphur froma given of tower i3 by conduit l8 which leads to a conquantity of gasoline. denser l9; wherein said vapors are liquefied. A further object is to obtain a maximum yield These low-boiling hydrocarbons are conveyed by 5 of stable cracked gasoline which will be substanpipe 29 to low boiling receiver 29.

tially free from sulphur. Other objects will be The low-boiling distillate is conveyed throughapparent as the detailed description of our inpipe 22 in amounts regulated by valve 23 to mixer vention proceeds. 2 5, which is preferably an orifice or knot-hole After extensive research on cracked gasoline mixer. Sulphuric acid of a concentration be- (pressure still distillate) prepared from different tween 89 and 100%, preferably about 98%, is 20 crudes, we discovered that the sulphur compounds supplied from storage tank 25 through pipe 26 are not uniformly distributed according to boilin amounts regulated by valve'2l to said-mixer ing point but are more concentrated in the higher 24. For a light out containing 0.2% sulphur, boiling fractions than in the lowerboiling fracabout 8 pounds of acid are mixed with 50 ga- 25 tions. We also discovered that the unsaturated lons of oil, for a light fraction containing 39% 25 hydrocarbons tend to be concentrated in the lowf sulphur about 20 pounds of acid are used to treat er boiling fractions and that the bulk of treat- 50 gallons ofoil, and for a light 6111 Containing ing losses therefore occur in these lighter frac- .96% sulphur about 44 pounds acid are used to tions. We have provided an improved treating treat 50 gallons of oil, 98% acid being used in to process wherein we make practical use of these each oi the above examples. 30 discoveries by separating the gasoline into two The mixture of the acid and oil is conducted or more fractions of successively higher boiling from mixer Zdby pipe 28 to separator 25, wherein range, treating the lower boiling fraction (which the sludge settles out and is withdrawn by pipe is low in sulphur and high in unsaturated hydro- 30, the treated gasoline being discharged through carbons) with a small amount of acid, treating pipe 35. l 35- the higher boiling fraction (which is high in sul- The heavy fraction is conducted'from the high. phur content and low in unsaturated hydrocarboiling receiver it through pipe 32 in amounts bons) with a larger amount of strong sulphuric regulated by valve 33 to mixer 33. Sulphuric I acid, and finally mixing the fractions to obtain acid of a concentration of from 93 to Mi l the desired properties for the final treated gasofor example 98%; isintroduced from storage tank 40 line. 35 through pipe "36 in the amounts regulatedby The invention will be more clearly understood valve 37 to said mixer. When the heavy cut from the detailed description which follows and contains .46% sulphur about 20 pounds of 98% from the accompanying drawing, whereinacid are used per 50 gallons of oil, when the Figure 1 is a flow diagram of our improved fraction contains .81% sulphur 43 pounds of 45 process. 98% acid are used to treat gallons of oil, and

Figure 2 is a characteristic graph showing the when the fraction contains 1.48% sulphur about Percentages o S p andlpelcentage 0 gaso- 60 pounds of 98% acid are used per 50 gallons line absorbed by acid plotted against the percent of oil.

50 of cracked gasoline di l The mixture of oil and acid is conveyed from 50 Referring to Fig. 1, pressure still distillate is mixer 34 by pipe 38 to separator 3Q wherein the introduced bypipe to through pipe still II and sludge is settled out and withdrawn by pipe 40 pipe l2 to a mid-point of fractionating tower l3. and the treated gasoline is withdrawn through The iractionating tower may be of any convenpipe I.

tional type and is preferably provided with bub- The treated gasoline from pipe II is mixed 55 with the treated gasoline from pipe Si in pipe 42, which discharges into a mixer 43, wherein the treated gasoline is mixed with water introduced through'pipe 44. From mixer 43, the ga oline and water are conveyed through pipe 45 to separator 46, impurities being withdrawn from the bottom of the separator by pipe 41 and the washed gasoline being withdrawn by pipe 40 which conveys it to mixer 49, where it is treated with doctor solution introduced through pipe 50.

The doctor solution is a conventional sodium plumbite which is made up by dissolving lead gasoline by pipe 54. v

The treatment with sulphuric acid'often leaves in the gasoline certainresin-forming or gumforming compounds which should be removed if stability of a long period of time is desired.

These resin-forming bodies are preferably removed by a second distillation, the treated gasoline being introduced by pipe 54 into a still (not shown) for final distillation.

The fundamental principles on which our invention isbased will be understood from the diagram in Fig. 2 and from the following tables.

sulphur in each fraction and (2) the percentage of pressure distillate absorbed by sulphuric acid. The results are as follows:

Crude No. I

Perc'entdis- Percent Percent tilled Ofl Sulphur Absorbed 10 .1 29 2o .2 25 30 .8 17 40 .4 s 50 .5 o 0 .0 6 70 .75

3 Crude No.1!

Percentdis- Percent I 1 Percent tilled ofl Sulphur Absorbed 1o .18 as r 20 .31 22 30 .55 18 4o .72 to .89 7 60 1.0o= 5 70 1.20 o

. Grade N0. III

Percsntdis- P t Percent tilledofl Bulph Absorbed 10- .38 25 20 .oo 19 30 1.25 16 40 1.41' 1 11 50 1.5a 9 60 -1.70 a 70 1.85 I 7 From Fig. 2 and from the above tables will be seen that the sulphur compounds are not uni formly distributed according to boiling point but these tend to be concentrated into the higher boiling fractions. Itis also shown that the unsaturated higher hydrocarbons are more concentrated in the lower boiling fractions. Therefore, by treating these fractions separately less acid can bflsed for lower boiling fractions. This will in turn result in a decreased gasoline ab:

sorption and as a result we will be able to increase the yield of gasolineand decrease the amount of acid required-by thesimple expedient of separately treating the fractions and subsequently uniting them.

The cracked gasoline, represented by Crude No. I in the above table, was fractionated into a light out having a .2% sulphur content and Using 8 pounds of 98% acid for the light out and 20 pounds of 98% acid for the heavy cutper 50 gallons of oil, a total of 14 pounds of acid was used per 50 gallons and a total treating loss of 5.7% resulted. When this gasoline was treated in one batch, 20 pounds of 98% acid were required per 50 gallons of oil and the treating loss was 9.10%. It will be seen. that 6 pounds of acid was saved for every 50 gallons of gasoline treated and that the loss was reduced from 9.10% to 5.7%, the difference being 3.40% of the gasoline treated which is equivalent to 37.7%

of the losses by, the old method of treatingall of the gasoline in one batch.

Similar tests on cracked gasoline from crude stock No. II showed'a'n acid saving of 12 /2% and a treating loss decrease of 4.38% of gasoline treated (which was equivalent to 25.3% of the loss by the old method of treating all of the gasoline in one batch).

Similar tests on cracked gasoline from crude stock No. 1II showed an acid saving of 7.1% and a treating loss decrease of 10.15% of the I gasoline treated (which was equivalent to 38.5%

of the losses by the old method of treating all of the gasoline in one batch). Examples might be multiplied indefinitely to show the saving eifected by our improved process.

15 the heavy out having a 116% sulphur content. v

1. The process for removing sulphur'from' cracked gasoline which comprises separating aquantity of cracked gasoline intp a high boiling fraction and a low boiling fraction, the volume of the low-boiling fraction being less than the volume of the high boiling fraction, treating the low boiling fraction with 89 to 98% sulphuric acid in the flity gallons of the fraction, treating the high boil- I ing fraction with 93 to IOU/ sulphuric acid in proportion of about eight pounds of acid for each comprises separatingfihe cracked gasoline into 9. high boiling fraction and a low boiling fraction of about equal volumes, treating the low' boiling fraction with 89 to 98% sulphuric acid in the proportions of about eight bounds of acid for I normally react with 93-98% sulphuric acid, which comprises separating the cracked gasoline into a low boiling fraction and a high boiling fraction of about equal volumes, treating the high boiling fraction with 93 to 104% sulphuric acid in proportions of about twenty pounds of acid for fifty gallons of said fraction, treatingthe low boiling fraction with 89 to 98% sulphuric acid in the proportion of about eight pounds of acid for about fifty gallons of said fraction, and reuniting said treated fractions to form the cracked gasoline.

4. The process of removing sulphur from cracked gasoline which comprises separating the cracked gasoline into a high boiling fraction and a low'boiling fraction, the volume of the high boiling fraction being not more than 30% greater than the volume of the low boiling fraction, treating the low boiling fraction with 89 to 98% sulphuric acid in the proportions of about eight pounds of the acid for about each 0.2% of sulphur per fifty gallons of the low boiling fraction, treating the high boiling fraction with 93 to 104 sulphuric acid in the proportions of about 20 pounds of the acid for about each 0.46% of sulphur per fifty gallons of the high boiling fraction, removing the sludge formed during the treating of the respective fractions, and reunitingthe treated fractions to form gasoline.

5. The process of removing sulphur from cracked gasoline which comprises separating a quantity of the gasoline into a low boiling fraction and a high boiling fraction, the volume of the low boiling fraction being less than 10% of the volume of the high boiling fraction, treating the low boiling fraction with 89 to 98% sulphuric acid in the proportions of about eight pounds of the acid for about 0.2% sulphur per fifty gallons of the low boiling fraction, treating the high boiling fraction with 93 to 104 of sulphuric acid in the proportions of about 20 pounds of the acid for about each 0.4% of sulphur per fifty gallons of the high boiling fraction, removing the sludge formed during the treating of the respective fractions, and reuniting the treated fractions to form I no gasoline substantially free from objectionable sulphur compounds and containing a large quantity of hydrocarbons that normally react with concentrated sulphuric acid.

6. The process of removing sulphur from cracked gasoline and at the same time preserving a substantial proportion of the compounds that normally react with strong sulphuric acid, which comprises separating the cracked'gasoline into a high boiling fraction and a low boiling fraction in the proportions of about forty percent of the high boiling fraction and sixty percent of the low boiling fraction, treating the low boiling fraction with 89 to 98% sulphuric acid in the proportions of about eight pounds of the acid for about each 0.2% of sulphur per. fifty gallons of the low boiling fraction, treating the high boiling fraction with 93 to 104% sulphuric acid in the proportions of about twenty pounds of the acid for about each 0.46% of sulphur per fifty. gallonsv of the high boiling fraction, and reuniting said treated fractions to form a cracked gasoline.

"I. The process of desulphurizing cracked gasoline and at the same time preserving a substantial portion of the hydrocarbons in said cracked gasoline which normally react with strong sulphuric acid, which comprises separating the cracked gasoline into a high boiling fraction and low boiling fraction, the volume of the high boiling fraction being equal to or not more than 10% greater gasoline which is'substantially free from sulphur and which contains a large quantity of hydrocarbons that normally react with strong sulphuric acid. v

8. The process of desulphurizing cracked gasoline which comprises separating the gasoline into a low boiling fraction and a high boiling fraction,

said low boiling fraction containing a small.

amount of sulphur-bearing compounds and a large proportion of hydrocarbons that are reactive with sulphuric acid, said high boiling fraction containing a large proportion of sulphur-bearing compounds, treating the low boiling fraction with 89 to 98% sulphuric acid in the proportions of about 8 pounds of acid for each 0.2% of sulphur per 50 gallons of the low boiling fraction, treating the high boiling fraction with 93 to mi sulphuric acid in the proportions of about 20 pounds of acid for each 0.46% of sulphurper 50 gallons of the high boiling fraction, and reuniting the treated fractions to form a cracked gasoline.

9. The process of desulphurizing cracked gasoline and at the same time preserving a substantial portion of the unsaturated compounds in said cracked gasoline, which comprises separating the gasoline into a low boiling fraction and a high boiling fraction, the volume of. the low boiling fraction being from one-third to one-fourth the volume of the high boiling fraction, treating the low boiling fraction with 89 to 98% sulphuric acid in the proportions of about 8 pounds of acid for each 0.2% of sulphur per 50 gallons of the lowboiling fraction, treating the high boiling fraction with 93 to IOU/ sulphuric acid'in the proportions of about 20 lbs. of acid for each 0.46% of sulphur per 50 gallons of high boiling fraction, and reuniting the treated fraction to form a cracked gasoline.

10.' The process of desulphurizing cracked naphtha which comprises separating the naphtha into a low boiling fraction and a high boiling Y fraction, the volume of the low boiling fraction being less than the volume of the high boilin fraction, treating the low boiling fraction with 89 to 98% sulphuric acid in the proportions of about 20 lbs. of the acid for about each 0.39% of sulphur per 50 gallons of the low boiling fraction, treating'thehigh boiling fraction with 93 to 104%% sulphuric acid in the proportions of about, lbs. of acid for about each 1.48% of sulphur per 50, gallons of the high boiling fraction,

removing the sludge formed-during the treating of the respective fractions and reuniting the fractions to form gasoline substantially free from objectionable sulphur compounds.

Joan n. 1100151151.,

ROBERT M. nos. 

